1. Field of the Invention
The present invention is directed to a composite plug system and a process to repair a hole in a tubular pipe. In particular, the present invention is directed to a composite plug system and a process to repair a hole in a tubular pipe which does not require any welding and may be used in high pressure tube and pipeline applications.
2. Prior Art
Pipeline holes or pipe “through wall defects” may be repaired in a variety of ways. In one existing technology, the damaged area of the pipe or pipeline is completely replaced. Total replacement of a damaged section requires the line to be shut down or, alternatively, the flow to be diverted while the damaged section is cut out and replaced by welding with a new cylindrical piece as a replacement. While this effectively solves the problem, it requires considerable welding and access to welding equipment.
An alternative technology is the use of pipe clamps which are, however, limited in the pipe geometries that are repairable (straight sections are best) and also require a uniform outer diameter pipe surface for proper sealing. This is not always the case in damaged pipelines in remote locations.
Another existing technology is welding patches over the holes. While this will often remedy the problem, not only must the fluid flow through the pipeline be stopped but the pipeline should properly be evacuated of all petroleum products to avoid explosion or fire.
Existing composite repair sleeves are also sometimes used but existing systems are not well suited for high pressure pipes or pipelines, such as those over 500 pounds per square inch (psi) where the holes are greater than 0.75 inches in diameter.
Various other repair patch systems have also been proposed in the past. For example, Cologna et al. (U.S. Pat. Nos. 4,588,626 and 4,820,564) discloses a repair patch kit for composite panel materials wherein a bolt head and a solid washer are inserted through a hole to be repaired. A flexible washer and a number of fabric plies are also inserted through the hole. On the exterior side of the hole is a plug 34 and a number of resin impregnated fabric plies. The assembly is held together by a nut secured to the shank of the bolt.
Kelly (U.S. Pat. No. 4,848,056) discloses a hole repairing device having a series of umbrella arms that open up once inside the wall or other structure.
Jewett (U.S. Pat. No. 5,033,949) discloses a hole repair device for repairing a damaged area to a planar surface such as a wall. The hole repair apparatus includes a flexible backing member 1 of a size greater than the hole in the panel. The backing member may be folded or otherwise inserted through the hole. A threaded bolt extends through the flexible patch member and extends outward from the panel. A front dam or panel is used to form an outer wall so that patching material may be inserted between the outer wall and the inner panel.
The repair of petroleum and petrochemical pipelines requires additional precautions as the fluids transported may be under high pressures and may be extremely flammable and combustible. An additional problem is present in petroleum transmission lines in Central and South America, for instance. Each day pipelines in these areas are illegally tapped by those who steal gasoline, petrochemicals and other petroleum products. When the pipeline operator determines the location of the illicit tap, the pipeline is turned off. Due to the remote locations and the frequency of these operations, pipelines are not fully evacuated of the petroleum products while repairs are made. A wooden plug is hammered into the hole and a flat piece of steel is welded over the hole to prevent the line from leaking. Since petroleum or other products may remain in or near the pipeline during this welding process, fires and explosions occur and several people perish each year. Additionally, the wooden plug hammered into the hole may present problems for equipment, such as pipeline pigs, or other cleaning or sensing equipment, that may travel within the interior of the pipeline.
There remains a need to provide a non-metallic tubular pipeline hole repair system that will function in high pressure applications.
There also remains a need to provide a tubular pipeline hole repair system that does not require any welding.